diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/updateWelcomePanel.php b/tests/phpunit/tests/admin/includes/ajax-actions/updateWelcomePanel.php
new file mode 100644
index 0000000000000..61761b0e181ab
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/updateWelcomePanel.php
@@ -0,0 +1,144 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_update_welcome_panel() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 3.1.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_update_welcome_panel
+ */
+class Tests_wp_ajax_update_welcome_panel extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Subscriber user ID.
+	 *
+	 * @var int
+	 */
+	protected static $subscriber_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id      = $factory->user->create( array( 'role' => 'administrator' ) );
+		self::$subscriber_id = $factory->user->create( array( 'role' => 'subscriber' ) );
+	}
+
+	/**
+	 * Tests successful update of welcome panel visibility.
+	 *
+	 * @dataProvider data_update_welcome_panel
+	 *
+	 * @ticket 65252
+	 *
+	 * @param mixed $visible The value for the 'visible' POST parameter.
+	 * @param int   $expected The expected meta value.
+	 */
+	public function test_update_welcome_panel_success( $visible, int $expected ): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST = array(
+			'action'            => 'update-welcome-panel',
+			'welcomepanelnonce' => wp_create_nonce( 'welcome-panel-nonce' ),
+		);
+
+		if ( null !== $visible ) {
+			$_POST['visible'] = $visible;
+		}
+
+		try {
+			$this->_handleAjax( 'update-welcome-panel' );
+		} catch ( WPAjaxDieStopException $e ) {
+			$this->assertSame( '1', $e->getMessage() );
+		} catch ( WPAjaxDieContinueException $e ) {
+			$this->assertSame( '1', $e->getMessage() );
+		}
+
+		$this->assertSame( $expected, (int) get_user_meta( self::$admin_id, 'show_welcome_panel', true ) );
+	}
+
+	/**
+	 * Data provider for test_update_welcome_panel_success.
+	 *
+	 * @return array<string, array{
+	 *     visible: mixed,
+	 *     expected: int,
+	 * }>
+	 */
+	public function data_update_welcome_panel(): array {
+		return array(
+			'visible true'  => array(
+				'visible'  => '1',
+				'expected' => 1,
+			),
+			'visible false' => array(
+				'visible'  => '0',
+				'expected' => 0,
+			),
+			'visible empty' => array(
+				'visible'  => '',
+				'expected' => 0,
+			),
+			'visible null'  => array(
+				'visible'  => null,
+				'expected' => 0,
+			),
+		);
+	}
+
+	/**
+	 * Tests update failure due to invalid nonce.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_update_welcome_panel_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST = array(
+			'action'            => 'update-welcome-panel',
+			'welcomepanelnonce' => 'invalid-nonce',
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'update-welcome-panel' );
+	}
+
+	/**
+	 * Tests update failure due to insufficient permissions.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_update_welcome_panel_insufficient_permissions(): void {
+		wp_set_current_user( self::$subscriber_id );
+
+		$_POST = array(
+			'action'            => 'update-welcome-panel',
+			'welcomepanelnonce' => wp_create_nonce( 'welcome-panel-nonce' ),
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'update-welcome-panel' );
+	}
+}